This project is an example application to show the Factory Method design pattern (DHBW - Semester 5 - Advanced Software Engineering)

##Scenario Our scenario is that we have developed a game in which users are able to create a vehicle based on different terrains. In a first version only one vehicle for one terrain - a car for the road terrain - is available. To provide developers adding more vehicles for different terrains, they are able to create mods with additional vehicles. The terrains are initially defined in the first version of the game.

Available Terrains:

• Road
• Offroad
• Industrial
• Underground
• Water
• Underwater
• Sky
• Space
• Transdimensional

Available Mods:

• none
• crank
• future

##Test it

You can test it by compiling and running the main method from Game class.

Example Output:

               DHBW SanPatrick               

|---------------------------------------------|
|        Terrain       |        Vehicle       |
|---------------------------------------------|
| ROAD                 | Car                  |
|---------------------------------------------|
| OFFROAD              | no vehicle available |
|---------------------------------------------|
| WATER                | no vehicle available |
|---------------------------------------------|
| INDUSTRIAL           | no vehicle available |
|---------------------------------------------|
| SKY                  | no vehicle available |
|---------------------------------------------|
| SPACE                | no vehicle available |
|---------------------------------------------|
| UNDERGROUND          | no vehicle available |
|---------------------------------------------|
| UNDERWATER           | no vehicle available |
|---------------------------------------------|
| TRANSDIMENSIONAL     | no vehicle available |
|---------------------------------------------|

Change mod by editing the mod.properties file in the properties folder.

##How it works

All vehicles have to implements the Vehicle interface.

public interface Vehicle {
    void steer();
}

The initial game provides a AbstractVehicleFactory class:

public abstract class AbstractVehicleFactory {

    public abstract Vehicle createVehicle(Terrain terrain);
}

This class provides the method createVehicle which should create a Vehicle based on the different terrains.

Each mod has to implement a VehicleFactory class extending the AbstractVehicleFactory class and override the createVehicle method.

Example implementation in crank mod:

public class VehicleFactory extends AbstractVehicleFactory {
    @Override
    public Vehicle createVehicle(Terrain terrain) {
        switch (terrain){
            case ROAD:
                return new Car();

            case WATER:
                return new Boat();

            case OFFROAD:
                return new Tank();

            case INDUSTRIAL:
                return new Forklift();

            default:
                return null;
        }
    }
}

Which mod is loaded is defined in the mod.properties file

mod=crank

If the game is started and the user creates a car the program has to decide from which VehicleFactory the createVehicle method has to be called.

To do this the game has a VehicleFactoryFactory class.

class VehicleFactoryFactory {
    static AbstractVehicleFactory createVehicleFactory() throws GameModNotFoundException {
        Properties modProperties = getProperties("mod");
        String mod = modProperties.getProperty("mod");

        String factory;

        if(mod.equals("none")){
            factory = "game";
        } else {
            factory = "mods." + mod;
        }

        factory += ".VehicleFactory";

        try {
            return (AbstractVehicleFactory) Class.forName(factory).newInstance();
        } catch (InstantiationException | IllegalAccessException | ClassNotFoundException e) {
            throw new GameModNotFoundException();
        }
    }
    
    ...
 }

The method createVehicleFactory reads the mod.properties file and than call the right class. For the crank mod:

mods.crank.VehicleFactory

After that the vehicle can be created

AbstractVehicleFactory factory = VehicleFactoryFactory.createVehicleFactory();
Vehicle vehicle = factory.createVehicle(Terrain.ROAD));

##UML

##Team Members

• Patrick Härtenstein
• Andreas Kießling
• Sebastian Ott
• Stefan Schneider